Condition	Characteristics
Atlantooccipital fusion	Partial or complete fusion of the atlas and base of the occiput; headache, neck pain, limb numbness and pain, weakness, tinnitus, visual disturbances, and dysphagia or dysarthria may occur
Flexion teardrop fracture	One of the most unstable types of cervical spine fractures; caused by combined flexion and compression forces
Jefferson fracture	Fracture of C1; usually caused by axial loading or hyperextension of the neck, resulting in a bilateral burst through the posterior arch and lateral masses; patients present with neck pain, normal range of motion, and a normal neurologic examination
Nonfusion of the posterior arch of the atlas	Mostly asymptomatic, although neck pain may occur; atlantoaxial instability and neurologic deficits are possible from cord impingement by a remnant of the posterior arch
Wedge fracture	Stable cervical fracture from flexion and axial loading of the neck; anterior vertebral body is compressed with no neurologic compromise; cervical orthosis used for management